There are numerous types of extension poles that can be used for painting or other applications, e.g., sweeping attachments, swimming pool cleaning nets, and which allow the user to adjust the overall length thereof. For example, such poles permit the attachment of a paint roller frame to the end thereof allowing the painter to paint walls and ceilings without the use of a ladder. Such poles typically utilize telescoping members for length adjustment purposes and some type of locking mechanism to interlock the telescoping members after the desired length of the pole has been attained. It has been found that these locking mechanisms usually have some type of inherent structural or operational disadvantages. For example, the adjustable extension pole disclosed in U.S. Pat. No. 5,220,707 (Newman, Sr., et al.) utilizes a locking mechanism comprising a Belleville-type washer arrangement which is connected to a pin which interlocks the outer telescoping sleeve within the inner telescoping sleeve. By depressing a push button operatively connected to the Belleville-type washer, the washer is deformed causing the pin to be withdrawn from the inner sleeve permitting the inner sleeve to be telescopically adjusted within the outer sleeve. Operationally, the aforementioned locking mechanism has some inherent disadvantages since, through use, the washer becomes fatigued causing the locking mechanism to malfunction. In addition, since a push button arrangement is used, paint can be easily entrapped under and around same affecting the "snap-action" ability of the Belleville-type washer.
Another tube or sleeve locking mechanism is disclosed in U.S. Pat. No. 3,596,946 (Burton, et al.) which utilizes an unidirectional cam lock arrangement to interlock the sleeves after the desired length of the extension pole has been attained. In this case, the inner and outer sleeves must be properly aligned in order to operate the cam locking arrangement and the cam locking arrangement is susceptible to paint becoming entrapped therein causing the malfunction of same. Another tube or sleeve locking mechanism is disclosed in U.S. Pat. No. 4,662,771 (Roe, et al.). In this case, the locking mechanism is comprised of a relatively complex ball and detent arrangement received between machined sleeves connected to the extension pole. The ball and detent arrangement is relatively costly to produce, and the resulting locking mechanism is susceptible to paint being entrapped therein resulting in the possible malfunction of same. A further tube or sleeve locking mechanism is disclosed in U.S. Pat. No. 3,603,623 (Widman). This locking mechanism utilizes oppositely wound coil springs which surround the inner tubular sleeve. By changing the bias on the springs which can be accomplished by moving external knobs on the outer surface of the locking mechanism, the inner sleeve is released permitting its telescopic adjustment within the outer sleeve. In this case, the coil springs are subject to fatigue and breakage, and the locking mechanism is susceptible to paint being entrapped therein due to its use of external knobs to change the bias on the springs within same. Lastly, U.S. Pat. No. 5,288,161 (Graves, et al.) discloses a locking mechanism which interlocks the end of an extension pole to the end of a paint roller frame. In this case, the extension pole is not telescopically adjustable, however, the locking mechanism permits the attachment of the pole, which can be any length, to the end of the paint roller frame. The locking mechanism disclosed in this patent is comprised of a lever arrangement which is external to the end of the pole, and thus, is very susceptible to paint being entrapped therein causing the locking mechanism to become difficult to operate or inoperable.
Because of the foregoing inherent disadvantages associated with presently available extension poles, it has become desirable to develop an extension pole locking mechanism that is durable, is easy to produce, assemble and operate and which is not susceptible to paint being entrapped therein.